Is Ebola Outbreak Entering New Phase?

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The reports of declining rates of new Ebola cases in Liberia,
announced by the World Health Organization on Oct. 29, fueled
hopes that the outbreak response is working, but experts are
cautioning that it is too soon to believe the epidemic has
entered a new phase, with slower growth.

Liberia has been one of the hardest-hit countries in the current
Ebola outbreak, with more than 6,500 cases and 2,413 deaths
reported in that country alone as of Oct. 31.

In addition to the perhaps positive news that the rate of new
cases in Liberia is not growing, WHO officials said the total
number of new cases in all three affected countries
— Liberia, Sierra Leone and Guinea — also may be
leveling off. Some WHO officials told BBC News that
they now expect the rate of new cases to be steady, at about
1,000 weekly cases in all three countries. That's a marked shift
from the increasing pace seen in weeks past, when the number of
new cases was growing exponentially. [2014
Ebola Outbreak: Full Coverage of the Viral Epidemic]

As with outbreaks of many infectious diseases, after the response
is implemented, people expect the spread of the disease to begin
to slow. Control measures as simple as educating people to avoid
touching other people and stopping
traditional burial practices, can limit the spread of the
virus.

But it is too soon to tell if that's the case with this Ebola
outbreak, said Dr. William Schaffner, an infectious-disease
specialist at Vanderbilt Medical Center in Nashville, Tennessee.

"I'm not so sure we are in that second phase just yet," Schaffner
said. "I hope it's true, but until we have a more sustained
period where the curve is flat, I think we're going to be hopeful
but cautious."

In early September, scientists had estimated that if the outbreak
were to keep growing at its current rate, by the beginning of
November, there would be nearly 9,900 cases in Liberia and more
than 20,000 total cases in all three countries. Another report
predicted an estimated
21,000 cases just in Liberia and Sierra Leone by Sept. 30.

The actual numbers are much better than those projections, with
about 13,500 cases in all three countries combined. But the
numbers are still too high, WHO officials warned, and the shift
in the speed of the outbreak's spread could be temporary. It's
possible that cases of the disease could increase in areas that
are now experiencing steady numbers of cases, WHO officials said.

It's possible that two more weeks of data could determine whether
the outbreak has moved into its next phase, meaning that cases
are not spreading as rapidly as anticipated, Schaffner told Live
Science.

Another concerning factor is that the geography of the disease
appears to have changed, with more Ebola cases turning up in
rural areas close to the major cities.
Researchers from the Centers for Disease Control and
Prevention recently reported that during the period from Aug.
31 through Sept. 23, the number of cases was highest in regions
where the three countries meet. But then, from Sept. 28 through
Oct. 18, the numbers were highest in rural areas around Liberia's
capital city of Monrovia and the country's Bong district, around
Sierra Leone's capital of Freetown and the country's northwestern
districts, and Guinea's Macenta district.

Another
report by the Africa Governance Initiative said that
every day in late October, on average, 12 new cases were reported
in the rural areas surrounding Freetown, compared with 1.3 cases
reported daily there in early September. This suggests the
outbreak is rapidly advancing in the rural parts of Sierra Leone
compared with several weeks ago.

"If you look at the map, one of the concerning things is how much
Ebola has penetrated into more rural areas of all of these
countries," Schaffner said. In rural areas, populations are
smaller, and people's homes are more scattered than in urban
settings, but these
places are also remote, far from the reach of public health
officials. "There may even be cases occurring in small villages
now that we don't know about," Schaffner said.

Part of the reason for the positive trend in Liberia is that
people there are practicing safe burial of patients who die of
Ebola, WHO Assistant Director-General
Dr. Bruce Aylward said last week. The bodies of Ebola victims
remain highly contagious after death, and have been a significant
route of infection during this outbreak.

Other key factors include the Liberian government’s public
education campaign and an increase in the capacity of treatment
centers, he said.